I just keep an old junky backpack in my trunk with targets, stapler, ears/eyes, tape, string, gloves, etc etc etc
Essentially all the range trip stuff that isn't guns/mags/ammo or specialized tools.
When I buy new targets, I eventually remember to stuff them in the backpack. It ends up being a mixed bag (NPI) of precision/zombie/shoot&see/improvised/blank/CMP/person/critter/etc targets, there's always something appropriate and/or amusing in there.